This returns nothing
reset();
var('i_B10 i_B6 i_B11 i_C10 i_C6 i_C11 beta i_in i_out i_E10 i_E6 i_E11');
solve([
i_C10==i_B10*beta,
i_E10==i_C10+i_B10,
i_C6==i_B6*beta,
i_E6==i_B6+i_C6,
i_C11==i_B11*beta,
i_E11==i_B11+i_C11,
i_E10==i_B11+i_E6,
i_E11+i_E6==i_in+i_out,
i_B11==i_B6,
i_in==i_B10+i_C11,
i_out==i_C10
], i_out)
[]
But it can be solved manually
reset();
var('i_B10 i_B6 i_B11 i_C10 i_C6 i_C11 beta i_in i_out i_E10 i_E6 i_E11');
i_C10=i_B10*beta
i_E10=i_C10+i_B10
i_C6=i_B6*beta
i_E6=i_B6+i_C6
i_C11=i_B11*beta
i_E11=i_B11+i_C11
i_B10=(i_E10==i_B11+i_E6).solve(i_B10)[0].right()
i_B10=i_B10(i_B11=i_B6)
i_C10=i_C10(i_B10=i_B10)
i_B6=solve(i_in==i_B10+i_C11(i_B11=i_B6), i_B6)[0].right()
i_out=i_C10(i_B6=i_B6)
i_out=i_out.simplify_rational()
i_out
(beta^2 + 2beta)i_in/(beta^2 + 2*beta + 2)
Why "solve" doesn't work? Do I need to set some assumptions or etc? Or is because i_out depends only on one variable? How to make "solve" function work in this case?